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Title: The role of kinetic instabilities in formation of the runaway electron current after argon injection in DIII-D

Abstract

Here, kinetic instabilities in the MHz range driven by runaway electrons (REs) have been observed for the rst time during the current quench in disruptions triggered by massive injection of argon in DIII-D. These instabilities are well-correlated with intermittent RE losses in the beginning of runaway electron current formation. The runaway current phase is not observed when the power of instabilities exceeds a threshold. Novel measurements of the RE distribution function during the current quench indicate that the instabilities appear when RE energy ( E RE) exceeds 2.5{3 MeV, the number of modes grows linearly with E RE, and their frequencies lie in the range 0.1–3 MHz, below the ion cyclotron frequency. Possible plasma waves exciting by REs in this region are proposed. Increase of the amount of injected argon decreases the E RE and increases the success rate of the runaway current formation, while increase of the pre-disruption plasma current acts in the opposite direction. No dependence on the pre-disruption core electron temperature is found.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2];  [3];  [4];  [5];  [6];  [7];  [3];  [7]; ORCiD logo [3];  [5];  [6];  [5];  [2]
  1. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Univ. di Milano-Bicocca, Milan (Italy)
  4. Univ. of California, Irvine, CA (United States)
  5. Istituto di Fisica del Plasma, Milan (Italy)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. Univ. of California San Diego, La Jolla, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1481733
Grant/Contract Number:  
FC02-04ER54698
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 12; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Plasma Phys. Control. Fusion; runaway electrons; kinetic instabilities; tokamak disruptions; massive gas injection

Citation Formats

Lvovskiy, A., Paz-Soldan, C., Eidietis, N. W., Molin, A. Dal, Du, X. D., Giacomelli, L., Herfindal, J. L., Hollmann, E. M., Martinelli, L., Moyer, R. A., Nocente, M., Rigamonti, D., Shiraki, D., Tardocchi, M., and Thome, K. E. The role of kinetic instabilities in formation of the runaway electron current after argon injection in DIII-D. United States: N. p., 2018. Web. doi:10.1088/1361-6587/aae95a.
Lvovskiy, A., Paz-Soldan, C., Eidietis, N. W., Molin, A. Dal, Du, X. D., Giacomelli, L., Herfindal, J. L., Hollmann, E. M., Martinelli, L., Moyer, R. A., Nocente, M., Rigamonti, D., Shiraki, D., Tardocchi, M., & Thome, K. E. The role of kinetic instabilities in formation of the runaway electron current after argon injection in DIII-D. United States. doi:10.1088/1361-6587/aae95a.
Lvovskiy, A., Paz-Soldan, C., Eidietis, N. W., Molin, A. Dal, Du, X. D., Giacomelli, L., Herfindal, J. L., Hollmann, E. M., Martinelli, L., Moyer, R. A., Nocente, M., Rigamonti, D., Shiraki, D., Tardocchi, M., and Thome, K. E. Fri . "The role of kinetic instabilities in formation of the runaway electron current after argon injection in DIII-D". United States. doi:10.1088/1361-6587/aae95a.
@article{osti_1481733,
title = {The role of kinetic instabilities in formation of the runaway electron current after argon injection in DIII-D},
author = {Lvovskiy, A. and Paz-Soldan, C. and Eidietis, N. W. and Molin, A. Dal and Du, X. D. and Giacomelli, L. and Herfindal, J. L. and Hollmann, E. M. and Martinelli, L. and Moyer, R. A. and Nocente, M. and Rigamonti, D. and Shiraki, D. and Tardocchi, M. and Thome, K. E.},
abstractNote = {Here, kinetic instabilities in the MHz range driven by runaway electrons (REs) have been observed for the rst time during the current quench in disruptions triggered by massive injection of argon in DIII-D. These instabilities are well-correlated with intermittent RE losses in the beginning of runaway electron current formation. The runaway current phase is not observed when the power of instabilities exceeds a threshold. Novel measurements of the RE distribution function during the current quench indicate that the instabilities appear when RE energy (ERE) exceeds 2.5{3 MeV, the number of modes grows linearly with ERE, and their frequencies lie in the range 0.1–3 MHz, below the ion cyclotron frequency. Possible plasma waves exciting by REs in this region are proposed. Increase of the amount of injected argon decreases the ERE and increases the success rate of the runaway current formation, while increase of the pre-disruption plasma current acts in the opposite direction. No dependence on the pre-disruption core electron temperature is found.},
doi = {10.1088/1361-6587/aae95a},
journal = {Plasma Physics and Controlled Fusion},
number = 12,
volume = 60,
place = {United States},
year = {Fri Nov 09 00:00:00 EST 2018},
month = {Fri Nov 09 00:00:00 EST 2018}
}

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